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Frivolousz21

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Re: The 2014 Melting Season
« Reply #3300 on: August 26, 2014, 06:11:07 AM »
In other news.  I think this is important to share.  We are crushing global sst records.

This is the same date set Bob Tisdale uses.  Below is the entire globe weeklly time series since 1990.  The past week came in right above .44C+. 

The one below that is back to 2002 and is easier to see.






We can see the NH is driving this and is torching.  A common summer theme since 2010.





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Michael Hauber

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Re: The 2014 Melting Season
« Reply #3301 on: August 26, 2014, 06:21:48 AM »
Yes interesting goings on, particularly in the North Pacific.  There are threads discussing ENSO and global temperature trends in the consequences section of this forum.  If you look at Bob Tisdale's reporting for the North Pacific there is a massive jump in SST for this region.  Perhaps there is a significant climate shift going on.  If so what consequences will this have for the Arctic?  Is the 'recovery' (regression to mean/slow decline or whatever) part of this climate shift?  Or will the climate shift (if it happens) very abruptly slam the Arctic back into turbo melt mode?
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Michael Hauber

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Re: The 2014 Melting Season
« Reply #3302 on: August 26, 2014, 06:27:17 AM »
No, Michael.  Maslowski's model-based projection is for 2016 +/- 3 years, so don't get excited just yet.  Remember also that similar comments were made after the 2009 season.

I'm also assuming that Maslowski's projection is basically the same as the one OSweetMrMath posted above me, which shows ice free in 2017.  As 2013 is outside the confidence interval, and 2014 expected to be further outside this consequence interval I was basically agreeing with OSMM that the projection is broken.  However there are two years in a row outside the 95% confidence interval early on, and 2014 is not done and may come out lower than I expect, so maybe the projection isn't yet dead, but only on life support in critical condition.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

deep octopus

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Re: The 2014 Melting Season
« Reply #3303 on: August 26, 2014, 06:29:41 AM »
Friv, I've been watching the global surface temperature set with great interest this year. I think the odds are good that 2014 will be the hottest year on record globally, with the oceans leading the way. On the global temp thread, I observed earlier that NCAR/NCEP has been seeing a warm August. In the last week, the daily data has shown an incredible spike in surface air temps. 1981-2010 anomalies were rising to near 0.60 C as of the 23rd. That's an atrocious number when translated to the 1951-1980 base NASA uses. It's been aggressive for a mostly ENSO-neutral year. Still waiting for El Niño to steal the show.

Steve Bloom

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Re: The 2014 Melting Season
« Reply #3304 on: August 26, 2014, 07:27:27 AM »
No, Michael.  Maslowski's model-based projection is for 2016 +/- 3 years, so don't get excited just yet.  Remember also that similar comments were made after the 2009 season.

I'm also assuming that Maslowski's projection is basically the same as the one OSweetMrMath posted above me, which shows ice free in 2017.  As 2013 is outside the confidence interval, and 2014 expected to be further outside this consequence interval I was basically agreeing with OSMM that the projection is broken.  However there are two years in a row outside the 95% confidence interval early on, and 2014 is not done and may come out lower than I expect, so maybe the projection isn't yet dead, but only on life support in critical condition.

No, Maslowski didn't use PIOMAS.  His is an Arctic Ocean regional model, not specifically a sea ice model.  So far it seems to be doing pretty well.  He has said his model has better results than the GCMs because it's much finer-grained, in particular allowing it to show the effect of encroaching warm Pacific water.  The next five years will tell the tale.

The graph from Wipneus isn't a model projection at all, rather it's just his curve-fitting extrapolation of PIOMAS data.  That said, and while I wouldn't bet anything on it being right, 2013/14 aren't enough to show it's wrong.

The lesson of the recent past is to expect a lot of variability in Arctic sea ice behavior as it continues a general decline, so as a general matter I don't think any sort of curve-fitting has much value (not to imply that Wipneus claimed otherwise).

viddaloo

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Re: The 2014 Melting Season
« Reply #3305 on: August 26, 2014, 07:28:45 AM »
Huge melt in the 100% concentration area at Uni–Bremen. Animation of Aug 24th & 25th.
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Frivolousz21

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Re: The 2014 Melting Season
« Reply #3306 on: August 26, 2014, 08:45:29 AM »
Friv, I've been watching the global surface temperature set with great interest this year. I think the odds are good that 2014 will be the hottest year on record globally, with the oceans leading the way. On the global temp thread, I observed earlier that NCAR/NCEP has been seeing a warm August. In the last week, the daily data has shown an incredible spike in surface air temps. 1981-2010 anomalies were rising to near 0.60 C as of the 23rd. That's an atrocious number when translated to the 1951-1980 base NASA uses. It's been aggressive for a mostly ENSO-neutral year. Still waiting for El Niño to steal the show.

Yes that is what makes it most interesting.  This is all happening with only a slight enso positive attm.
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Jim Hunt

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Re: The 2014 Melting Season
« Reply #3307 on: August 26, 2014, 12:43:34 PM »
The view from on high of the cyclone currently swirling over the "Laptev Bite":

http://GreatWhiteCon.info/resources/arctic-sea-ice-images/summer-2014-images/#Laptev

Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Jim Hunt

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Re: The 2014 Melting Season
« Reply #3308 on: August 26, 2014, 12:47:26 PM »
I believe projecting a polynomial fit onto PIOMAS data was behind projections of an ice free Arctic as early as 2013 (but more likely later) which were made in 2007.

For the truth about what other people said the BBC said Wieslaw Maslowski said in 2007, including an audio recording of the man himself, please see (and hear!):

http://GreatWhiteCon.info/2013/09/shock-news-why-isnt-the-arctic-ice-free/
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

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Re: The 2014 Melting Season
« Reply #3309 on: August 26, 2014, 01:43:22 PM »
Friv, I've been watching the global surface temperature set with great interest this year. I think the odds are good that 2014 will be the hottest year on record globally, with the oceans leading the way.

I figure the odds are about 1 in 3.  Reasoning is explained over in the "Global Surface Air Temperatures" thread.

iceman

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Re: The 2014 Melting Season
« Reply #3310 on: August 26, 2014, 02:08:16 PM »
This is interesting. JAXA is indicating that the northwest passage is about to open up via the Parry Channel. Guess we'll have to stay tuned.
Interesting indeed, especially as only 10 days ago an open NWP looked unlikely.  However, only a couple of warm days before the end of August, and the ice in the McClure Strait has become more mobile recently, so southerly winds might push it back into the open water before it melts out enough for passage.
    Odds are also narrowing a bit on the southern loop, a variation on the Amundsen route.

Bruce

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Re: The 2014 Melting Season
« Reply #3311 on: August 26, 2014, 05:28:30 PM »
As a fit for the data, it's really good. But we want to use it to predict when the sea ice volume will go to zero, and it runs into problems for this purpose. The first thing to notice is that although most points fall inside the confidence interval, the data point for 2013 is above the confidence interval. The fact that the last actual value is off the curve should lead to doubt about the curve's ability to predict the future.
This is akin to claiming that since the weatherman didn't accurately predict today's rain, then all climate science is bunk. Surely you're aware that the data we're dealing with are noisy?

Quote
This curve's claim to fame is that the 2010 data predicted the 2011 and 2012 data points, but to me that just points up the danger of arbitrary curve fitting. Just because a particular curve works for some period in the future, that does not mean it will work for other periods.
The curve's "claim to fame" isn't that it accurately predicted one or the other year, it's that it is an overall good fit to the data. And yet you're willing to reject it because it didn't fit the data for some arbitrarily short period? Seems a little like Skeptical Science's "Escalator": http://www.skepticalscience.com/graphics.php?g=47

I don't want to be in the position of defending that particular fit, as there is danger in extrapolating any time series -- especially one that is controlled by so many factors and competing feedbacks -- but the point of the graphic is that ice loss has been proceeding at an accelerating pace and if that trend continues an ice-free arctic is an inevitability, and sooner rather than later. Whether it is 2017 or 2019 isn't really the point.


cesium62

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Re: The 2014 Melting Season
« Reply #3312 on: August 26, 2014, 06:14:14 PM »
This is akin to claiming that since the weatherman didn't accurately predict today's rain, then all climate science is bunk. Surely you're aware that the data we're dealing with are noisy?

No, it's more like if the weatherman predicts it's going to rain in California in June because of the increasing rate of rain storms that occur from December through April.

Fitting curves to graphs is fun.  But without a plausible physical model to back up the chosen curve, it's just numerology.

cesium62

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Re: The 2014 Melting Season
« Reply #3313 on: August 26, 2014, 06:27:02 PM »
Whether it is 2017 or 2019 isn't really the point.

In the context of this discussion board, that really is the point.  We have various people plausibly arguing for a 2026 to 2030 time-frame.  We're trying to understand what physical processes and feedback mechanisms might produce an early or late melting point.  We're trying to understand how much noise is available in the system.  It's not enough for us to say "we're pretty sure the arctic will be ice-free this century".

As you said, the data has a lot of noise.  Why do we think that 2007 through 2012 are signal and not noise?  is a good fit to noisy data really telling us something?  Or have we overfit the noise?

Rubikscube

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Re: The 2014 Melting Season
« Reply #3314 on: August 26, 2014, 07:38:10 PM »
Together with the usual suspects (2007, 2012 and 2013) I've this week added 2005, which saw by most measures the lowest pre-2007 minimum, to give some longer term context. 2005 and 2007 are AMSR-E while the rest are AMSR-2.
« Last Edit: August 26, 2014, 07:58:05 PM by Rubikscube »

Steve Bloom

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Re: The 2014 Melting Season
« Reply #3315 on: August 26, 2014, 09:13:16 PM »
I believe projecting a polynomial fit onto PIOMAS data was behind projections of an ice free Arctic as early as 2013 (but more likely later) which were made in 2007.

For the truth about what other people said the BBC said Wieslaw Maslowski said in 2007, including an audio recording of the man himself, please see (and hear!):

http://GreatWhiteCon.info/2013/09/shock-news-why-isnt-the-arctic-ice-free/

Jim, your post text unfortunately doesn't distinguish between Maslowski's model projection and his own curve-fitting (which latter I don't think he put inappropriate weight on).  I assume the audio clarifies this point, but that's well into tl;dr territory, or more aptly tl;dl. 

OSweetMrMath

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Re: The 2014 Melting Season
« Reply #3316 on: August 26, 2014, 10:58:58 PM »
As a fit for the data, it's really good. But we want to use it to predict when the sea ice volume will go to zero, and it runs into problems for this purpose. The first thing to notice is that although most points fall inside the confidence interval, the data point for 2013 is above the confidence interval. The fact that the last actual value is off the curve should lead to doubt about the curve's ability to predict the future.
This is akin to claiming that since the weatherman didn't accurately predict today's rain, then all climate science is bunk. Surely you're aware that the data we're dealing with are noisy?
The whole point of the confidence intervals on the graph is to account for the uncertainty due to the noise. The data point for this year will be far outside the confidence interval for this year. This implies that either the model for the noise is not correct, or the trend line is not correct. And by not correct, I mean not useful for future predictions. Do you rely on the weather predictions a week in advance? If yesterday's prediction for today's high temperature is off by 20 degrees, do you still trust yesterday's prediction for the high for a week from today? (How often this year have the weather predictions a week out in this thread turned out to be incorrect?)
Quote
Quote
This curve's claim to fame is that the 2010 data predicted the 2011 and 2012 data points, but to me that just points up the danger of arbitrary curve fitting. Just because a particular curve works for some period in the future, that does not mean it will work for other periods.
The curve's "claim to fame" isn't that it accurately predicted one or the other year, it's that it is an overall good fit to the data. And yet you're willing to reject it because it didn't fit the data for some arbitrarily short period? Seems a little like Skeptical Science's "Escalator": http://www.skepticalscience.com/graphics.php?g=47
I've said this before, but I'll say it more strongly. You can choose any predicted value at all for the ice volume for 2014, and I can give you a curve which exactly goes through every point on the graph including your chosen prediction for 2014. Does that make it a good prediction? No, obviously. Fitting the existing data is not by itself a sufficient condition for good future predictions. I don't reject the predictions because it didn't fit the data for an arbitrarily short period. I reject the curve because there's no reason to assume that just because the curve has been a good fit until now, it will continue to be a good fit in the future.
Quote
I don't want to be in the position of defending that particular fit, as there is danger in extrapolating any time series -- especially one that is controlled by so many factors and competing feedbacks -- but the point of the graphic is that ice loss has been proceeding at an accelerating pace and if that trend continues an ice-free arctic is an inevitability, and sooner rather than later. Whether it is 2017 or 2019 isn't really the point.
The question is not whether it's 2017 or 2019. The question is whether it's 2017 or 2100. Physical climate models tend to predict that the Arctic sea ice will entirely melt during the summer for the first time after 2050. These models have generally failed to keep up with reality, but that doesn't make this curve a better prediction.

cesium62

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Re: The 2014 Melting Season
« Reply #3317 on: August 27, 2014, 02:32:37 AM »
Do you rely on the weather predictions a week in advance?

Heh.  I live in California.  For about 6 months out of the year I can pretty much make my own weather predictions and rely on them.  ;-)
« Last Edit: August 27, 2014, 02:38:12 AM by cesium62 »

viddaloo

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Re: The 2014 Melting Season
« Reply #3318 on: August 27, 2014, 04:46:28 AM »
Quote
[666]   Go Up

Uh–oh. Going up!  ;D

Map reminds me of Africa, with the Sahara as the MYI. (Just had to state that before everything changes shape.)
« Last Edit: August 27, 2014, 07:29:57 AM by viddaloo »
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Bruce

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Re: The 2014 Melting Season
« Reply #3319 on: August 27, 2014, 05:38:00 PM »
Fitting curves to graphs is fun.  But without a plausible physical model to back up the chosen curve, it's just numerology.
No, it's statistics. The model is that more heat is being added to the system and it's causing decreased September sea ice coverage. If curve B fits the data better (statistically) than curve A, and curve B's fit is statistically significant, and curve B's parameters are statistically justified, then B is the better representation of the data than A. If you don't think so, it's up to you to come up with a) something better, or b) explain why you don't think the indicated trend will continue.

SATire

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Re: The 2014 Melting Season
« Reply #3320 on: August 27, 2014, 05:47:20 PM »
Fitting curves to graphs is fun.  But without a plausible physical model to back up the chosen curve, it's just numerology.
No, it's statistics. The model is that more heat is being added to the system and it's causing decreased September sea ice coverage. If curve B fits the data better (statistically) than curve A, and curve B's fit is statistically significant, and curve B's parameters are statistically justified, then B is the better representation of the data than A. If you don't think so, it's up to you to come up with a) something better, or b) explain why you don't think the indicated trend will continue.
One opinion to that topic from the physics side: Fitting a function to data can be used to refuse a model but never to prove it. With the chi^2 number you may get a probability to reject a model. If the noise is to large, you can not securely reject a function... But you will never proove that a model is right by fitting - you just may come to the conclusion that the data does not exclude that function (yet, because not enough statistics = not enough data available). A infinite number of functions may describe the same data - as long as they do not move to often e.g. 2 sigma away from the data, they stay in the game...

Trying to find a model to describe the world by fitting a function is magic. That is well beyond physics ;-)
Just my 2 physical c.

Bruce

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Re: The 2014 Melting Season
« Reply #3321 on: August 27, 2014, 06:08:28 PM »
The whole point of the confidence intervals on the graph is to account for the uncertainty due to the noise. The data point for this year will be far outside the confidence interval for this year. This implies that either the model for the noise is not correct, or the trend line is not correct.
If you establish confidence intervals then, by definition, some points will fall outside of them.

Quote
I've said this before, but I'll say it more strongly. You can choose any predicted value at all for the ice volume for 2014, and I can give you a curve which exactly goes through every point on the graph including your chosen prediction for 2014.
This is a straw man. You can use (for example) the Lagrange interpolation formula to exactly "fit" a polynomial to any sequence of numbers whatsoever, but you'd be hard pressed to find a real problem for which all of the extra parameters are statistically justified (vs. a simpler model). Any measure of a model's goodness of fit should also include an analysis of the number of parameters. And any model that requires as many parameters as there are data points can be rejected outright.

One can play all sorts of games with curve fitting, but I don't see that as the case here. The exponential appears to fit the data better than a straight line, and is a fairly simple, common model. Again, I'm not in a position to defend it, no do I want to, but I think it makes a valid point about what we're seeing: sea ice losses have accelerated. A model that doesn't make that point misses the point.

Bruce

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Re: The 2014 Melting Season
« Reply #3322 on: August 27, 2014, 06:13:02 PM »
Trying to find a model to describe the world by fitting a function is magic. That is well beyond physics ;-)
Just my 2 physical c.
So F = ma is magic? I'll be sure to tell Newton.

SATire

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Re: The 2014 Melting Season
« Reply #3323 on: August 27, 2014, 06:28:10 PM »
Trying to find a model to describe the world by fitting a function is magic. That is well beyond physics ;-)
Just my 2 physical c.
So F = ma is magic? I'll be sure to tell Newton.
lol!
No - that function was found by thinking and worked quite well when fitted to experimental data - a while, until precision got better and that function was rejected e.g. in the case of high velocities. Then Einstein came up with a new formular which until now could not be rejected by fitting to any data. But that is not a proove for Einsteins thoughts - so there may be more precise measurements in the future prooving Einstein wrong... That is life in physics. And such is life in the Arctic: Future melting may proove any function wrong. But until then, all functions not yet rejected are all in the game. And they predict nothing, because they are so many. 

Bob Wallace

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Re: The 2014 Melting Season
« Reply #3324 on: August 27, 2014, 08:08:23 PM »
Quote
No, it's statistics.

Statistics are great for description.  And statistics can work pretty well as predictors in situations where new variables aren't popping up.

So far the Arctic has been warming faster than the planet in general.

What if (pure speculation) the recent changes in jet stream behavior change heat distribution patterns and going forward the Arctic warms more slowly? 

What if (pure speculation) the extra moisture in the atmosphere creates very heavy early freeze season cloud cover, blocks heat escape, and the Arctic forms far less ice over the winter?

We've tossed a stick of dynamite into the fish pond.  We can't predict where the fish are going to land or the number of pisces pieces .  Previous counts of fish on land don't help us out here.

ChrisReynolds

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Re: The 2014 Melting Season
« Reply #3325 on: August 27, 2014, 09:51:55 PM »
Trying to find a model to describe the world by fitting a function is magic. That is well beyond physics ;-)
Just my 2 physical c.
So F = ma is magic? I'll be sure to tell Newton.

To add to what SATire replied. Not getting personal here - this is a sideswipe at all the statistical extrapolators here.

Exactly what physical model are you saying underlies the exponential fit that gives 2016 +/-3 years, when...

1) All the physical models (including PIOMAS) when run as forecast show a sigmoidal type function (implying a Gompertz type stat model). You can argue safely that most of the older GCMs are behind the curve, but this does not mean all qualities of their projections are wrong. Note - Maslowski's extrapolation of NAME is not using NAME to forecast.

2) Applying the same model to other months of the year gives highly implausible results such as no April sea ice by the 2040s. And nobody can claim cloud radiative feedback to help them here because the curve fitting is done on past data, and there is no evidence of a strong CRF playing a role in that (e.g. Screen & Simmonds dismissal of Graveson et al).

3) 2014 has seen a massive pulse of thick MYI injected into the ice system (PIOMAS - almost all the volume gain is due to ice in the Central Arctic between 3 and 3.9m thick). Surely this delays the ice free prospect by at least 5 years (2010 to 2014 melt seasons work). That puts us at around 2020.

It is a finding in GCMs (and PIOMAS) that the process of volume loss changes as the pack thins to mainly FYI, with the winter growth of ice overcoming summer losses and leading to a long tail (thickness/growth feedback). How does your model factor this in?

PS In case people think I'm making up the thickness/growth feedback.
http://psc.apl.washington.edu/wordpress/impacts-of-reduced-sea-ice-on-atmospheric-heat-precipitation-rates-and-ice-production/

Lord M Vader

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Re: The 2014 Melting Season
« Reply #3326 on: August 27, 2014, 10:13:37 PM »
I thought we were discussing the melting season of 2014 in this thread? However, I'll put my opinion about the future and when the Arctic may become ice-free. What I'm waiting, and surely many other with me, is when the big Goliath El Niño will come. IMO it will come, the question is when rather than "if".. So far, the atmosphere have been working overtime to prevent an abrupt climate change by putting the excessive heat down in the deep oceans but this can't last for ever. Sooner or later there will be a point when we'll see a very rapid warming.

About some years after the El "Goliath" Niño it will take a few years before the extra heat reach the Arctic. My guess is that we'll see a rapid warming to come most lately at 2020 if not before. At that time there will be a rapid decline in the Arctic SIE minima. While we mainly focus on individual years the trend is extremely clear: looking at JAXA numbers per decade reveals an AVERAGE SIE minima about 1 MILLION km2 less than the preceeding decade. If that trend continues the 2010-2019 average will be about 4,5 Mn km2. The 2020-2029 average then should be about 3,5 Mn km2 with the possibility for an extreme outlier to go down below 2 Mn km2. By 2030-2039 the numbers would be 2,5 Mn km2 by September and surely there should be a huge variation in SIE minimum with the plausibility of individual "ice free" years.

The Pacific is trying to make an el Niño but a quick look at the SSTs reveal that to establish a temperature gradient between the east and west Pacific the heat has to be redistributed which at this moment should be much slower than earlier times when an El Niño have emerged.

Latest NOAA forecast for the Niño 3.4 index is that it will be above 0,5 during next spring. That seems ominious as such scenario would probably make it a lot easier to get a really big El Niño. The only historical reference that I can think about is 1986-1988 which had a "double up".

What are your ideas?

mdoliner

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Re: The 2014 Melting Season
« Reply #3327 on: August 27, 2014, 10:52:10 PM »
Trying to find a model to describe the world by fitting a function is magic. That is well beyond physics ;-)
Just my 2 physical c.
So F = ma is magic? I'll be sure to tell Newton.
lol!
No - that function was found by thinking and worked quite well when fitted to experimental data - a while, until precision got better and that function was rejected e.g. in the case of high velocities. Then Einstein came up with a new formular which until now could not be rejected by fitting to any data. But that is not a proove for Einsteins thoughts - so there may be more precise measurements in the future prooving Einstein wrong... That is life in physics. And such is life in the Arctic: Future melting may proove any function wrong. But until then, all functions not yet rejected are all in the game. And they predict nothing, because they are so many.

F=ma is not something that can be checked by experiment. It is a definition.

Adam Ash

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Re: The 2014 Melting Season
« Reply #3328 on: August 27, 2014, 11:54:25 PM »
F=MA is also a little odd, mentally, as it leads one to the appreciation (that Newton did not get to) that it requires infinite force to move a body from a state of rest in a given reference frame to a state of being in motion because the time required to 'move' from a state of rest to a state of being in motion is zero, thus acceleration is infinite, which requires an infinite force to induce.  Our experience (our 'experiment') denies this.  The way out of this conundrum is that at rest the mass of a body has to be zero, and its mass is some function of its velocity over that starting instant.  Nice.

plinius

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Re: The 2014 Melting Season
« Reply #3329 on: August 28, 2014, 12:34:44 AM »
F=MA is also a little odd, mentally, as it leads one to the appreciation (that Newton did not get to) that it requires infinite force to move a body from a state of rest in a given reference frame to a state of being in motion because the time required to 'move' from a state of rest to a state of being in motion is zero, thus acceleration is infinite, which requires an infinite force to induce.  Our experience (our 'experiment') denies this.  The way out of this conundrum is that at rest the mass of a body has to be zero, and its mass is some function of its velocity over that starting instant.  Nice.

Adam Ash - in case this was not meant to be a satire, I would strongly recommend reading an introduction into infinitesimal calculus and revisit your mechanics I lecture.

@ mdoliner: The exact meaning of F = ma lies a bit in interpretation and how you set up your axioms.

@ Vader: I am a bit surprised how the heat of an El Nino should reach the arctic after several years? You get an instantaneous effect by manipulating the jetstream/Rossby wave locations, which in my naive view would be far more important. Also an El Nino rather releases energy from the Earth system (or currently slows the accumulation) by heating the surface up for a short period of time.  Perhaps someone here knows better than I do.

Adam Ash

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Re: The 2014 Melting Season
« Reply #3330 on: August 28, 2014, 02:04:48 AM »
Thanks Pilinius!  And before I begin my read, could you tell me please what time it takes for a body to move from a state of rest, to a state of motion?

But I digress...
« Last Edit: August 28, 2014, 02:30:20 AM by Adam Ash »

Adam Ash

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Re: The 2014 Melting Season
« Reply #3331 on: August 28, 2014, 02:07:29 AM »
A new paper on heating in the Atlantic, and the link to Arctic fresh water heading south...
Aug 26, 2014
Cause of global warming hiatus found deep in the Atlantic Ocean
http://environmentalresearchweb.org/cws/article/yournews/58328

'A pool of freshwater from melting ice now sitting in the Arctic Ocean, for example, could overflow into the North Atlantic to upset the cycle.'

viddaloo

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Re: The 2014 Melting Season
« Reply #3332 on: August 28, 2014, 03:58:54 AM »
Some happy amateur statistics points to the discussion about ice melt projection functions:

1) While area and extent data are more available and also more visual, they say less than volume about how much melt went on in that particular season. True, the 'target' is zero for all data groups, but the physical (3D) reality is best represented by 3D volume numbers. (This would of course change a bit when/if all areas become thin 1–2 m ice.) Melting work – extremely energy requiring – has to be done on the 3D ice, although the area where work can be done (from above and below) is roughly the same for 2D and 3D ice.

2) Demands and requests for elaborate physical models to predict the first Zero Ice Day (ZID?) are frequent, but are we sure they are a) possible or even b) better than a purely mathematical function, at describing the current and future ice melt trend? I would lean heavily towards a 'no' on both accounts. Recent developments in nearby Iceland as well as the unpredictability of the ENSO and their aftermaths, suggest that a fully accounting physical model for the Arctic Ocean melt trend is next to impossible. At best, such a formidable and laborious project would also have to adjust its projections following yearly major events, just as the mathematical whole–system functions will have to take new data points into account for updated projections of the elusive ZID.

3) Already mentioned by others, but a purely mathematical function with its inherent confidence intervals is not proven wrong by one or two data points beyond those confidence intervals. The function doesn't say no data can deviate from the projection, it merely says this is the area where you'll most likely find future data points. Also, any model or function, like my own 3rd Degree Polynomial function, must be expected not to be correct at first run, say, in August 2014, but should rather be expected to be the best available projection for an August or September ZID at the point of publication, with further updates and adjustments along the way. The fact it allows for easy inclusion of new data points that can then quickly and with no doubt or hesitation whatsoever be drawn upon to produce *even better* projections, is in fact a strength, not a weakness. The fact that a 9 year old can run the model off of a future web page and get updated and accurate ZID projections also suggests robustness. Simplicity and whole–system nature means fewer things can go wrong. (If Iceland goes BANG, it will be a new datapoint, or several, yet it's in no way a crisis for this model. It's by definition adjustable to unforeseen events.)

4) September 2012 only contributed 1.1% of the total ice mass — or 259 km³ – to the 2012 yearly melt, or minimum. 259 km³ melted in half a day in June of 2007, in less than 12 hours. 99% of the 2012 melt work was already done by the last day of August. This suggests that the first ZID event may well come in August, following an exceptionally successful start of the melting season in a way hotter year than 2012, as these outlying years go. If the overall meltdown % is raised all the way from 2012's 84% of the Winter Maximum up to 99 or even 100% — in such an extraordinary year — it is also highly likely that no more work is needed on the ice by September 1st. My simple math model suggests August & September will crash in the same year, or two adjacent years. I think August will say 'Oi! Join the club!' to September.

Your thoughts on all of these, please!
« Last Edit: August 28, 2014, 08:14:36 AM by viddaloo »
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greatdying2

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Re: The 2014 Melting Season
« Reply #3333 on: August 28, 2014, 05:59:52 AM »
Thanks Pilinius!  And before I begin my read, could you tell me please what time it takes for a body to move from a state of rest, to a state of motion?

But I digress...

Isn't that why Newton invented calculus? (Yes, he did "get to it.")

P.S. Perhaps it takes one chronon?
http://en.wikipedia.org/wiki/Chronon
« Last Edit: August 28, 2014, 06:05:23 AM by greatdying2 »
The Permian–Triassic extinction event, a.k.a. the Great Dying, occurred about 250 million years ago and is the most severe known extinction event. Up to 96% of all marine species and 70% of terrestrial vertebrate species became extinct; it is also the only known mass extinction of insects.

jdallen

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Re: The 2014 Melting Season
« Reply #3334 on: August 28, 2014, 09:24:21 AM »
Trying to find a model to describe the world by fitting a function is magic. That is well beyond physics ;-)
Just my 2 physical c.
So F = ma is magic? I'll be sure to tell Newton.

To add to what SATire replied. Not getting personal here - this is a sideswipe at all the statistical extrapolators here.

<snippage>

3) 2014 has seen a massive pulse of thick MYI injected into the ice system (PIOMAS - almost all the volume gain is due to ice in the Central Arctic between 3 and 3.9m thick). Surely this delays the ice free prospect by at least 5 years (2010 to 2014 melt seasons work). That puts us at around 2020.


While I respect the citations, and acknowledge the buffering provided by thicker ice, I'm not sure this is a safe assumption.  It will help, for certain, but even with the "pulse", there's a lot more heat lose, and the weather is becoming far less predictable.

That said, I doubt we'll see a melt-out (sub one million KM2 of ice) in the 2016/2017 time frame. However, that won't be an outcome caused by thickening ice.  Considering the total collapses of MYI in 2007 and 2012, I'm not sure that's a sufficient impediment to melt.  The lack of a melt out will be an outcome of weather matched to the yet insufficient net heat available to support it.  I'd watch the winter max volume, area and extent rather than what things look like at minima.  I think that will be more diagnostic.
This space for Rent.

SATire

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Re: The 2014 Melting Season
« Reply #3335 on: August 28, 2014, 10:35:20 AM »

Exactly what physical model are you saying underlies the exponential fit that gives 2016 +/-3 years, when...
Chris, I remember we discussed that elsewhere some time ago. The albedo-feedback of decreasing sea-ice in summer is underlying the exponential increase of sea ice loss:
The warming is proportional to the ice-free area. Integrating that most simple differential equation results in the exponential increase of sea-ice loss until it is all gone.

However - other factors may play a mayor role, too. Like those you collect in the "long-tail thread". That may be similar to the problems of applying "F=ma" in the case you have also sticking friction (F=Fr) and/or sliding friction (F=mv) involved - in that case the model is just to simple and will fail.

So in future fitting of the exponential function to sea-ice data may proove the model "albedo-feedback is driving the sea-ice loss now" wrong - maybe allready this or next year... Things like this make the observations so interesting theses days.
« Last Edit: August 28, 2014, 10:45:01 AM by SATire »

cesium62

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Re: The 2014 Melting Season
« Reply #3336 on: August 28, 2014, 11:22:15 AM »
2) Demands and requests for elaborate physical models to predict the first Zero Ice Day (ZID?) are frequent,

I haven't seen any demands or request for elaborate physical models.  I think we'ld be quite happy with simple models.  If the temperature of the world were staying constant; we'ld expect the amount of ice in the arctic to stay roughly constant over many years.  If the temperature of the world were increasing linearly, which seems plausible when we look at ocean heat uptake graphs, I'd expect ice to be dropping linearly.  So a simple model that explains why ice would drop superlinearly in response to a linear increase in heat, or a simple model explaining why there is a superlinear increase in heat is all that's needed to justify the exponential curve fit to PIOMAS volume.

cesium62

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Re: The 2014 Melting Season
« Reply #3337 on: August 28, 2014, 11:37:34 AM »
The albedo-feedback of decreasing sea-ice in summer is underlying the exponential increase of sea ice loss:
The warming is proportional to the ice-free area. Integrating that most simple differential equation results in the exponential increase of sea-ice loss until it is all gone.

Ah, right on time.  Thanks.

DavidR

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Re: The 2014 Melting Season
« Reply #3338 on: August 28, 2014, 12:07:04 PM »
cesium62,
a simple model would be to  consider the area of water that is able to  freeze.  Pi*R^2 is a simplistic representation of this in the Arctic.  As the oceans warm and the radius of the circle is reduced the area that is able to freeze is reduced exponentially. On top of that there is more heat available per unit area to warm the circle  that can freeze so the radius of the circle is also reduced by  an exponential factor  each year. The combination of these two  factors give a decline that  is exponential. 
The extra heating from more open water due to the albedo difference between ice and water will also  accelerate the decline. 
Toto, I've a feeling we're not in Kansas anymore

nukefix

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Re: The 2014 Melting Season
« Reply #3339 on: August 28, 2014, 01:13:41 PM »
F=ma is not something that can be checked by experiment. It is a definition.
Well yes, in the sense that any equation with a "=" is a definition. It is very simple to check with an experiment that indeed force and acceleration co-vary linearly.

SATire

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Re: The 2014 Melting Season
« Reply #3340 on: August 28, 2014, 01:23:18 PM »
cesium62,
a simple model would be to  consider the area of water that is able to  freeze.  Pi*R^2 is a simplistic representation of this in the Arctic.  As the oceans warm and the radius of the circle is reduced the area that is able to freeze is reduced exponentially. On top of that there is more heat available per unit area to warm the circle  that can freeze so the radius of the circle is also reduced by  an exponential factor  each year. The combination of these two  factors give a decline that  is exponential. 
The extra heating from more open water due to the albedo difference between ice and water will also  accelerate the decline.
DavidR, sorry that I have to interfere and to start hairsplitting. Maybe you wanted to say "is reduced quadratically" instead of exponential. If you remember high school math, the exponential function is the solution for something, if the derivative of that something is proportional to that something. That is the nice thing of the exponential function - it describes things that change proportional to itself.
And the thing fittet to the sea-ice data to test the "albedo-feedback-model" is not the exponential decline - that exp(-t) function is the thing with the tail like in radioactive decay or discharge of a capacitor and so. No - here we talk about exponential increase of sea-ice loss - that is A - B exp (t) and results in the most rapid loss. This latter function will probably be the first one rejected by curve fitting, if the sea-ice area does not hit zero soon.

Nightvid Cole

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Re: The 2014 Melting Season
« Reply #3341 on: August 28, 2014, 01:42:29 PM »
Together with the usual suspects (2007, 2012 and 2013) I've this week added 2005, which saw by most measures the lowest pre-2007 minimum, to give some longer term context. 2005 and 2007 are AMSR-E while the rest are AMSR-2.

Why don't you have a map comparing this year to 2011, the year most resembling in terms of the shape of the ice pack?

DavidR

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Re: The 2014 Melting Season
« Reply #3342 on: August 28, 2014, 01:51:29 PM »
SATire,
Oxford Dictionary:
  • exponentially: becoming more and more rapid.
  • quadratic: Involving  the second and no higher power of an unknown quantity or variable.
I'm reading that as 'quadratic is a specific  example of an exponential relationship'.
In the example I  have given quadratic could apply  to the simple circle model but not to the more complex model where heating and albedo affect the radius used in the circle.
Toto, I've a feeling we're not in Kansas anymore

SATire

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Re: The 2014 Melting Season
« Reply #3343 on: August 28, 2014, 02:47:27 PM »
DavidR, in math or physics:
exponential function of the variable x: 2.718 to the power of x
quadratic function: x to the power of 2
Only the latter describes the area of the circle you mentioned.

sorry for beeing off-topic. Maybe we should move to some new thread "basic math" or so

crandles

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Re: The 2014 Melting Season
« Reply #3344 on: August 28, 2014, 02:56:16 PM »
Oxford Dictionary:
  • exponentially: becoming more and more rapid.

That is very vague.

Exponential growth is much more specific:
http://en.wikipedia.org/wiki/Exponential_growth

Quote
Exponential growth occurs when the growth rate of the value of a mathematical function is proportional to the function's current value.



The graph illustrates how exponential growth (green) surpasses both linear (red) and cubic (blue) growth.

(We are talking growth of melt volume, not exponential decay of remaining volume.)
« Last Edit: August 28, 2014, 03:01:42 PM by crandles »

Bruce

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Re: The 2014 Melting Season
« Reply #3345 on: August 28, 2014, 06:38:05 PM »
F=ma is not something that can be checked by experiment. It is a definition.
You couldn't possibly be more wrong. At the risk of taking this thread further off topic, F = ma is a purely empirical relationship. Which is to say that it can only be supported or rejected by experiment and observation. And to explicitly make my earlier point, which seems to have been missed, there is nothing that says that it is either unique or that there isn't a better fit to the data that has yet to be discovered. Thus it is "magic" by the earlier definition, but "science" by every other.

Getting closer to on-topic, Chris, I know we disagree on this topic, and I respect your opinion (and even admit that you may end up being right). But the models suffer from the same problem that simple curve fitting does: they only work as long as the future looks like the past. The models, of course, notoriously missed the rapid melt of the last decade.

With such a complex system, there are a large number of competing factors, and each has its advocates as to its dominance. The "right" hypothesis may be out there (possibly yours!), but the space is crowded. My belief is that there is more than enough heat to melt all of the ice already, and it is just a matter of time until the "perfect storm" (possibly a real storm) delivers it. With the added heat of each passing year, the "storm" needs to be a little less perfect. When you melt 85% of your starting ice in a season, it doesn't take a lot to kill that last 15%.

viddaloo

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Re: The 2014 Melting Season
« Reply #3346 on: August 28, 2014, 06:39:57 PM »
PS: See this thread for a dedicated discussion of this graph & thought.

Another Google Graph. Shows May & June increasingly important for the total melt, overtaking August & July, respectively.

*Edit* Interpretation: While we see other months also increasing due to the overall increase in meltout, ie because of the melting effect of a warmer ocean, May and June increase way faster and in an accelerating manner. This may be due to the known feedback mechanisms that are most prevalent when the Sun is strongest/longest lasting (albedo, meltponds, methane heat trapping).

What are your explanations for this difference in the 2 pre–solstice months?
« Last Edit: August 29, 2014, 05:09:17 PM by viddaloo »
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ChrisReynolds

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Re: The 2014 Melting Season
« Reply #3347 on: August 28, 2014, 08:15:52 PM »
Getting closer to on-topic, Chris, I know we disagree on this topic, and I respect your opinion (and even admit that you may end up being right). But the models suffer from the same problem that simple curve fitting does: they only work as long as the future looks like the past. The models, of course, notoriously missed the rapid melt of the last decade.

I'm sorry but saying the models "only work as long as the future looks like the past" is a total misconception. The models are physical models based on physics worked out theoretically and underpinned, in some cases 'tuned by', obervational work. They do not depend on the past as a guide, they use physics. What comes in the future will unfold due to real world physics, not due to magic or a 'new physics'.

The models missed the rapid melt after 1995, but that is not grounds for dismissing them entirely. There's a British phrase that is appropriate here - don't throw the baby out with the bathwater - that seems quite apt. Yes the GCMs have failed to keep pace with events, but the logical conclusion of that is not necessarily that events will continue on the same trajectory to a rapid crash. The models showing that the thickness-growth feedback will overcome the ice/ocean albedo feedback that has driven the post 1995 volume loss may be what is about to happen, indeed may already be happening, in the real world (of course you know I am becoming more convinced that this is what is happening - give it another five years and we'll see Central Arctic PIOMAs volume flatlining once more).

EDIT - forgot to add, we had perfect storms in 2007 and 2012. Now 2007 couldn't be expected to lead to zero ice - there was too much there to begin with. One can be more favourably disposed to a 2012 event leading to a crash to zero, but even that would need exceptional rates of volume loss through the season to get to zero.



The red plots show the amount of volume loss needed to get the 2007 to 2013 average seasonal melt rates to take volume to zero from April volume. This is far and above anything that has been seen in the Arctic from 1978 to 2014, 36 years.

I don't want to be rude but I have to be frank. There are many people pleading 'black swan events' of different sorts, e.g. ENSO/PDO/AMO related matters, to overturning of the Arctic Ocean bringing the Atlantic Water into contact with the ice. If I was relying on such events to cause a rapid crash, I would not feel I had strong confidence in such an event.

Anyway, say 2012 had taken us to zero, unlikely but not inherently improbable (IMO), what would have followed with the same weather would have been 2013 and 2014. In such a situation one would not be justified in calling 'ice free', the correct call would be 'blip'.
/EDIT

SATire,

As you know, I accept Lindsay & Zhangs hypothesis that it is the ice albedo feedback that has driven the 1995 to 2010 volume loss. I just think that since 2010 the thickness-growth feedback has overcome it. Ice albedo feedback remains as strong as ever, but it won't lead to a rapid crash out.
« Last Edit: August 28, 2014, 08:29:19 PM by ChrisReynolds »

Rubikscube

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Re: The 2014 Melting Season
« Reply #3348 on: August 28, 2014, 09:36:27 PM »
What are your explanations for this difference in the 2 pre–solstice months?

Very interesting graph (and question) indeed. My first thought is that an ever increasing factor of the ice still left to melt after solstice is "hard to melt ice" stacked up north of CAA. Perhaps it is further proof that there is an Gompertz tail in the making.

You must be trolling, or at least you have the mathematical knowledge of a troll.

DavidR is certainly not a troll, and I don't think his mathematical skills should be drawn into question because of a minor remark about mathematical terms. Especially when he probably is rigth.

Quoting wiki
Quote
In general, an exponential function is one of the form bx, where the base is "b" and the exponent is "x".
However, nowadays the term exponential function is almost exclusively used as a shortcut for the natural exponential function ex

Furthermore, Wikipedia's article about exponential growth is about cbx functions, which includes both natural and quadratic functions. I hope we don't have to discuss this minor detail any further.
« Last Edit: August 28, 2014, 09:43:33 PM by Rubikscube »

viddaloo

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Re: The 2014 Melting Season
« Reply #3349 on: August 28, 2014, 10:01:06 PM »
What are your explanations for this difference in the 2 pre–solstice months?

Very interesting graph (and question) indeed. My first thought is that an ever increasing factor of the ice still left to melt after solstice is "hard to melt ice" stacked up north of CAA. Perhaps it is further proof that there is an Gompertz tail in the making.
Thanks, Rubikscube. I think so, too. We also have to remember that the ocean is warmest after the Summer Solstice, so June melting more ice than July, and May melting more than August, gets even stranger that way.

I also find it hard to comprehend that July doesn't get as much Sun related warming as June, when Sun warming up to Solstice equals the cooling after Solstice (equivalent for May & August). Maybe the remaining ice is harder to melt, as you suggest? But with as much warmth from the Sun, and with a much warmer ocean, it seems mysterious. Anyone?
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